Various apparatus and arrangements are known which provide method and apparatus for feeding and applying a generally flat cover to a cooperative opening in a moving container where an outwardly extending substantially horizontal flange surrounds the opening to the container and where an upwardly directed peripheral flange surrounds a portion of the horizontal flange. The present invention provides a cover feed means in timed relation with the container conveyor means so the cover is automatically placed on the advancing conveyor so each cover engages the container first flange and is then urged into place over the container opening where the cover is secured.
Such apparatus and arrangements are useful in diverse applications but are particularly useful in supplying covers and applying such covers to the opening of aluminum foil tray-type food containers, for example, deep-drawn aluminum trays, as the trays are moved along a high speed process line after they have been filled.
In such applications, it is essential that the covers be accurately located and secured in place to avoid disruption of the process line and to, equally as important, prevent improper packaging.
Various prior art devices have been utilized for placing flat covers over container openings as, for example, shown in U.S. Pat. Nos. 3,263,393 and 2,595,849.
In the food processing and filling industry, trays are passed along a conveyor line and filled with selected food, covers are placed on the moving containers and sealed. In such applications, including other packaging arrangements to which the present invention applies, the material to be packaged is usually placed in a deep-drawn tray, for example, an aluminum tray, where a generally horizontal peripheral flange surrounds the opening of the material receiving portion of the tray and an upstanding lip is provided around an outer portion of the flange and adapted to be folded over to retain the cover which is placed on the horizontal flange.
One device previously used for placing a flat cover on the tray opening has included a vacuum pick-up which lifts the cover from a stack and transfers the cover to a moving container as it passes the cover station. In such arrangements, the cover is placed on the container from a direction transverse to the direction of movement of the container so complex and expensive timing arrangements are required to properly place the cover.
In another, more common arrangement, as shown in U.S. Pat. No. 2,595,849, covers are removed from a stack and fed from above the conveyor line in the direction of travel of the conveyor where the cover is retained and supported on a mechanism while being placed over the opening to the container by spring tension means acting upon the fingers to grip the cover where the release of the fingers is effective by positive action of the mechanism and where means are provided to control movement of the cover. In such arrangements, it has been required to very accurately index the cover feed so the leading edge of the cover precisely engages the front edge of the container just inside the leading edge of the upstanding flange or else the cover is misplaced in the container and may overextend the front end of the container leading to improper packaging.